grisly (adj.)

Old English grislic (in compounds) "horrible, dreadful," from root of grisan "to shudder, fear," a general Germanic word (cognates: Old Frisian grislik "horrible," Middle Dutch grisen "to shudder," Dutch griezelen, German grausen "to shudder, fear," Old High German grisenlik "horrible;" of unknown origin; Watkins connects it with the PIE root *ghrei- "to rub," on notion of "to grate on the mind." See also gruesome, to which it probably is connected in some way. Related: Grisliness.